The present invention relates to a vinylidene fluoride resin fiber and a process for producing the fiber. The vinylidene fluoride resin fiber according to the present invention is useful for fishery materials, particularly for fishlines used for landing weighty fishes such as tuna.
Vinylidene fluoride resin fibers have been popularly used for fishery materials such as fishlines and fishing nets as this fiber has a refractive index close to that of water and tends to be concealed from the view in water.
A fiber used for landing weighty fishes such as tuna is required to have a significantly large diameter such as not less than 0.5 mm, but it is not enough to merely enlarge the fiber diameter for catching weighty fishes.
In the case of tuna, for instance, it is said that when the fish takes the bait, it makes a nose-dive in water at a speed of around 60 km/h, giving a sharp impact force to the fiber, Therefore, the fiber used for catching weighty fishes is required to meet certain specific quality requirements, that is, it is required, for instance, to be capable of landing fishes with no fear of snapping even when given a strong impact force such as mentioned above, and yet to have good handling property.
As a result of-the present inventors' intensive studies on the subject matter, it has been found that by melt-spinning a feedstock resin, cooling the spun filament at a specified temperature and preheating the resultant filament at a specified temperature before stretching, the obtained vinylidene fluoride fiber has an excellent transparency, high tensile elongation and tensile strength, and a high energy at break. The present invention has been attained on the basis of the above finding.